merchauser

had a non pressure leak on my PSD pump, that was resolved with a small seal from a Honda motorcycle shop.
prior to this, the PSD was working properly.

I have flushed and bleed my system, in the past, using the WSM and Ott/Veninger write up, but what is the difference
in the procedure for priming the pump.

is the bleeder open or closed for priming? I have been energizing the pump for only 5 seconds at a time, with a 5 second
break, and then repeat. a little tentative because I have read it is easy to burn up the motor. rather go super slow, than make
an expensive mistake. is 5 sec not enough time? when I energize the pump, the fluid level is not going down.

SteveG

I'm not sure I understand what is happening. The system won't pressurize if the bleeder is open. What happens with the bleeder closed and you start the car?

merchauser

hi steve,
system has been empty for a few months. (dry) I am trying to first prime the dry pump, and once I can do that, I will be able to
bleed.
will close the bleed and make more attempts. up to 15 seconds at a time

jcorenman

If the pump is dry then getting it primed can be a challenge. Start with the bleeder at the solenoid valve body, open it (one turn or so) and stick a length of plastic tubing on it to a catch-can. Jumper the pump for 10-15 seconds, odds are nothing will come out but if so then you are done-- back to the flushing instructions.

The next step is to get fluid into the pump body instead of air. Grab your Mity-Vac with its little catch-can, hook it up to the tubing from the bleeder valve and try to suck fluid through the pump from the reservoir. If you get fluid, then disconnect the Mity-Vac and try the pump again. If you get fluid then back to the flushing instructions. If not, rinse and repeat.

For those reading along, here are the flushing instructions from the 928 Int'l website: http://www.928intl.com/repair/psd1.pdf

merchauser

should I disconnect the solenoid connector while attempting to prime??

merchauser

can someone comment on HOW difficult the pump is to prime??? having a bit of a time of it, and done for the day.
I have a vacuum brake bleeder that I connected to the bleeder, but could not draw any fluid. was advised not to run
the pump for more than a minute at a time, which I have done repeatedly, without any luck

any other tricks or tips??? caveat: pump had a bad internal seal that created a slow drip, but the PSD was working
fine prior to removal.

jcorenman

Try this thread: https://rennlist.com/forums/928-foru...-psd-pump.html

How much vacuum does the brake bleeder pull?

merchauser

[QUOTE]Try this thread: https://rennlist.com/forums/928-foru...-psd-pump.html=left
=left
How much vacuum does the brake bleeder pull? [QUOTE]

I had read that thread before and wonder on post #8, are you saying to first try with solenoid connection disconnected.

I am not pulling any fluid with the brake bleeder: zip

merchauser

I would like to try to use my power bleeder, but I have the reservoir with the vent on the side, not on the cap
last time I tried this is got fluid spewing out the vent line

merchauser

I capped the reservoir nipple, and used a vacuum cap with clamp to block the vent tube, but still managed to make a nice mess
attempting to use my pressure bleeder. with the vacuum bleeder I was not able to draw any fluid out, even when running the pump.

any other suggestions??

merchauser

today I took the PSD out (again) and took the motor off to examine. everything looked OK, so I put it together and back in the car.
this time, I put my mityvac on the solenoid bleeder @ 25". ran pump while pulling vacuum and still will not prime.

???????

Kevin in Atlanta

Does the motor start to struggle after running for a few seconds? That would indicate the unit is building pressure.

merchauser

not building pressure and no sign of struggling, like it did before.

I saw your write up about rebuilding. it seems that there are no internal parts to service? only to clean? the unit was super clean inside, but all I did
was take off the motor from the pump

should I be pulling a stream of fluid from the bleeder using the mityvac??

merchauser

everything was remarkably clean, and no evidence of crud or debris. jim informed me of the fluid path from the top of pump housing, thru the check valve, and then interconnects to the accumulator, pressure switch, and hard line.

I have a feeling my issue is with the check valve. not able to draw fluid or air from the pump thru the check valve the valve seems to be blocking flow



I blew some air into the hole that you see at about 6 o' clock in this photo. I think this hole is for supply from the reservoir, and travels north to the check valve

does anyone know about the check valve, function and removal?

FredR

The check valve is there to prevent the fluid in the pressurised reservoir from back flowing through the pump once the pump shuts down. Thus you should be able to draw flow through it by applying vacuum on the accumulator side of the check valve or should be able to force flow through it from the pump side of the check valve providing the bleed valve is open.